worth an ask..

J

ja3mie

A3 1.8t Quattro Sport!
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im not too fussed by this, but thought its worth an ask!

SOMETIMES... my car (a3 TQS - AJQ engine) will hesitate..

its only if im in say 3rd or higher gear at lower speeds pulling..

its really hard to explain but..

when it does it.. it pulls ALOT harder and faster than normal. then drops power!

now, i dont know if its pulling faster than normal when it does it, or if its pulling slowly normally and it occasionly pulls fine then cuts power? but im more sure thats its fine normaly and pulls faster when it plays up! there is no lights on or anything..

anyone have any ideas? if not im not too fussed, as if i want to go fast i just use the gears properly, is just if im doing say 30 and try a 4th gear pull!

cheers in advance!
 
Just to add..

its standard apart from baileys DV30 and a drilled airbox! (done it before these mods too)

i also serviced the car today.. - oil, filter, fuel filter, cleaned air filter, and spark plugs and it still does it..

tried 99 fuel too as the bloke used to run it on that and it made no difference just cost more lol
 
You need at least 2 tanks of high octane for the ecu to adjust itself.. And I find that mine runs better on high octane then it does on normal unleaded. Have you got VCDS?
 
It may be something like a faulty N75 valve. It's not able to control the wastegate properly
 
i dont have vag com. i really need to get it though! wheres the best place?

i just thought.. earlier i did think when it done it earlier i heard the DV "tishhh"! but, i have done the n249 bypass so surely it cant be the DV opening?

how can you check the n75 valve?

cheers
 
It sound slike a similari-ish problem to how mine bogs down but mine is only very slightly.

I think min is the MAF sensor as it's 94,000miles old.
 
well mines 122k old so could be! lol have you tried cleaning it out? i may try this tommorow!
 
Been told to avoid cleaning it out as in the long run it will make no difference. A new one is about £115 (-£45 surcharge) from Audi. Similar priced on ECP.

If you don;t go to a dealer don't get anything cheap - Bosch is recommened.
 
i get trade so i suppose its worth doing! im going to clean it out first though, they get gunked up! just spray some carb cleaner on it :) yes it will get blocked again soon.. but so will a brand new one? hmm
 
A brand new one will last a lot longer.. a LOT longer. Had a few people tell me when they have cleaned theirs out it's lasted no more than a week.

I had a feeling mine would have gone at some point but half expected it to go caput before now. It's urprising they last more than 90,000 miles.
 
check the hose that comes from the top boost pipe to the n75 valve, sounds like its struggling to control boost properly
 
if im honest.. i dont know where the n75 valve is? lol
 
just read another post about the n75 valve.. someone said they had to replace this when they had overboost problems!

the other day my mate cleared an overboost problem from the car using vagcom.

could it be overboosting hence sometimes it pulls like a monster then cuts?
 
you know when you were asking about the n249 valve and you thought it was that little black box by the turbo intake pipe, thats the n75 valve


ja3mie said:
243066_10150189297607499_568782498_7076184_839919_o.jpg
Click to expand...

ja3mie said:
from what i can figure out its the little box with the connector on it thats just above the intake pipe on the picture? i may be wrong though!
Click to expand...

Cookstein said:
the little box above the TIP with the electrical connection is the N75 valve which controls boost.
Click to expand...
 
Last edited:
i see! is there any way to test it? resistance check or anything?

cheers! i love this forum, no other forums are ever this hepfull! lol
 
audi upgrades
urm...... there is supposed to be a 25-35 ohm resistance across the two connector pins on the n75 valve
 
your legend mate! got my snap on multi meter out so will go have a play. first time i got to use it! lol

thing im thinking, as its intermitant, will it read fine now.. hmm. let ya know in a few minutes!
 
ive got the same probem at the minuite mate ive done the n249 bypass and had the n75 unplugged for about 2 hrs, after completeing the bypass, reconnecting the n75 the car was running sweet as foooook no sign of boost hesitation at all, 2 days later fault appeared again :wtf: guessing new n75 is in stall
 
does it bring a light on having the n75 valve undone? i will go have a play
 
not sure mate wouldnt of thought so ive not been in the car while it was unplugged yet gonna try it later tho......its a pain of a problem, mine felt well more responsive the other day and a hell ova lot more power, im determined to get that back now just havent got the cash at min get it to a garage
 
im now going to check the resistance of my valve and compair it to the results i should be getting (mentioned above)
 
Don't run with it unplugged cause youll be running with uncontrolled boost and could do some damage!! First thing to do is to check both pipes going into the n75 for splits thoroughly!!
 
i think he means electrically unplugged so the wastegate opens at acctuator pressure, so it runs at low boost levels rather than high
 
Ohhhh duh lol, probably worth unplugging the maf and seeing if it runs better too
 
Yeah unplugged the n75 before and it runs alot slower must have a split pipe somewhere or loose connection am gona change the boost hoses on the n75 and dv them seem very squishy lol
 
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